Update building instructions

a good place to trigger a test on the opensimulator site

BUILDING.txt

@@ -17,13 +17,22 @@ Prereqs:
  * On some Linux distributions you may need to install additional packages.  
     See http://opensimulator.org/wiki/Dependencies for more information.
 
+ * May also use xbuild (included in mono distributions)
+ * May use Monodevelop, a cross-platform IDE 
+
 From the distribution type:
  * ./runprebuild.sh
- * nant
+ * nant (or xbuild)
  * cd bin 
  * copy OpenSim.ini.example to OpenSim.ini and other appropriate files in bin/config-include
  * run mono OpenSim.exe
 
+=== Using Monodevelop ===
+
+From the distribution type:
+ * ./runprebuild.sh
+ * type monodevelop OpenSim.sln
+
 === References ===
  
 Helpful resources: